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Be Serious about B. cereus

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Presentation on theme: "Be Serious about B. cereus"— Presentation transcript:

1 Be Serious about B. cereus
Bacillus cereus

2 Bacillus cereus Gram positive Spore former Facultative aerobe
Germinates quickly (20-30 minutes) pH range Temperature range (41°F-122°F) Optimum (95°F-104°F)

3 B. cereus Two types of food-borne intoxications (not infections)
Diarrheal form Emetic (vomiting) form

4 Diarrheal form Onset time 6-18 hours Duration <24 hours
Resembles Clostridium perfringens food poisonings Caused by heat-labile enterotoxin (heat-unstable) Often affiliated with foods made with meat or vegetables

5 Emetic form Onset time 0.5-6 hours Duration <24 hours
Caused by heat-stable enterotoxin Often affiliated with properly prepared fried rice that is not held at proper temperature Resembles Staph aureus food poisonings

6 CDC Risk Factors 1. Food from unsafe sources 2. Inadequate cooking
3. Improper holding temperatures 4. Contaminated equipment 5. Poor personal hygiene

7 Outbreaks First reports in Europe in the early 1900’s
Linked to outbreaks in 1950’s Worldwide recognition by the 1970’s 35 outbreaks reported in U.S. from

8 Maine Outbreak September 22, 1985
Restaurant patrons began exhibiting symptoms while at restaurant 11 persons of 36 served Onset time 30 minutes to 5 hours. Hibachi steak was positive for B. cereus Fried rice, mixed veggies, & hibachi chicken were negative

9 Maine Outbreak (cont.) Fried rice made from leftover boiled rice
Storage practices unknown for boiled rice (may have been stored at room temperature)

10 Virginia Outbreak July 21, 1993 Two jointly owned child care centers
Catered lunch Chicken fried rice was implicated Rice was cooked the night before, cooled at room temperature then refrigerated Rice was pan-fried with cooked chicken and delivered to centers by 10:30 am

11 Virginia Outbreak (cont.)
Rice was held w/o refrigeration Served at noon w/o reheating Median onset time 2 hours CDC risk factor – improper holding temperatures

12 Sources of B. cereus Cereals Vegetables Spices
Pasteurized fresh & powdered milk Dried beans Potatoes

13 CDC Risk Factors Involved
Inadequate cooking Improper holding temperatures Contaminated equipment

14 References Bad Bug Book, USFDA MMWR 43(10):1994 Mar 18
MMWR 35(25):1986 Jun 27 Todar’s Online Textbook of Bacteriology –

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